Trying to understand rotation of parented objects (relative rotation?)
A simple way is to just use Clear and Keep Transformation (Alt P) on the child to visualize the final rotation (global/world). As soon as you check the value, just press Ctrl Z to UNDO the Clear Parent.
The numbers of Top (child object) do not change because they exhibit rotation without the influence of the parent. To update the values, make sure the child inherits the rotation from the parent with Alt P.